Diaphragm for dictaphones, etc



May 15, 1923. 1,455,745

H. c. EGERTON DIAPHRAGM FOR DICTAPHONES, ETC

Filed May 9, 1919 nuenfoz @51 @Hozmmg Patented May 15, 1923..

UNITED STATES PATENT OFFICE.

HENRY C. EGERTON, OF RIDGEWOOD, NEW JERSEY.

DIAPHRAGM FOR DICTAP'HONES, ETC.

Application filed May 9, 1919. Serial No. 296,016.

for Dictaphones, Etc, of which the following is a specification, taken in connection with the accompanyingdrawing.

This invention relates especially to diaphragms having attached or incorporated styli suitable for use in connection with dictaphones or similar devices. The diaphragms may be advantageously madeof one or more layers of fabric carrying incorporated cured phenolic condensation cementing material, such as bakelite, condensite, or redmanol varnish compositions. The central portions of the diaphragms may be advantageously stifl'ened by being given a projecting and more or less coned up contour, the relatively fiat edge portions of the diaphragm inside the clamping members used givlng relatively great flexibility so as to allow the desired vibration of the central portions of the diaphragm to which one or more styli may in some cases be permanently connected during the molding and curing of the im regnated diaphragm fabric, if desired. apphire or other cutting OI recording styli may also be con veniently secured to such a coned up or otherwise stiffened diaphragm center by inserting them through .an accurately posifibre may be used in whole or in part in connection with the phenolic condensation cementing and stiffening material" and the one or more styli may be adhesively secured to the stifi'ened vibrating portion of the diaphragm in such cases.

The accompanying drawings show in a 4 somewhat diagrammatic way various illustrative embodiments of this invention, and.

Fig. 1 1s a side view of a diaphragm for the purpose.

Fig. 2 is an enlarged side sectional view thereof; and p 7 Fig. 3 is a side View partly in section showing a different construction.

The diaphragm may as indicated in Fig. 1 comprise a relatively stiffened coned up central portion 2 to. which the stylus 3 may be cemented or otherwise rigidly secured and a relatively flat yieldable edge portion 1 may be formed on the diaphragm to facilitate its normal vibration under working conditions. Such a diaphragm may conveniently formed of one or more layers of cotton cloth, cotton batting, or other suitable fabric carrying and preferably quite thoroughly impregnated with phenolic condensation cementing material, such as bakeliteor condensite varnish compositions which may be present to the extent of forty to sixty per cent more or less in the dried impregnated fabric. Such impregnated fabric may when heated and softened be molded under pressure in a suitably shaped mold so that the heated and softened fabric may be forced into the desired contour and cured under pressure at such temperatures as 300 to 320 Fahrenheit, more or less for fifteen to thirty minutes or so so as to preferably substantially completely cure' the phenolic condensation cementin material and greatly strengthen and sti en the cotton or other fibrous material with which it is incor orated. By forming suchia diaphragm of several thicknesses of thin muslin preferably having lo'osely twisted threads the diaphragm wall may have a thickness of six to eight thousandths of an inch more or less when two ounce fabric is used and of course a greater number of layers of fabric or other fibrous material may be employed Where each layer is thinner, or a relatively less number of layers of thicker material may be employed in some cases, and the wall thickness of the diaphragm may of course vary considerably according to the I particular service desired.

The stylus, such as 3, of sapphire, glass, hard metal or other suitable material may be originally molded in the diaphragm, and secured thereto bythe phenolic condensation cementing material, or in some cases the 7 diaphragm may be originally formed in molds having such contour as to have a re- I uantities enforced stylus seat or securing portion, if desired, containing relatively greater proportions of the cementing and stiffening material in some cases, and by forming a cavity within the point of the male mold the high molding pressure tends to force some of the softened ormelted phenolic condensation cementing material into such a cavity to form some such reenforcement or lump as 6 shown in Fig. 2 which greatly stiffens and strengthens the material. After the diaphragm is molded the hole 7 for the stylus may be bored, punched or otherwise formed in suitabl jigs or locating devices and then the stylus 3 which may have a cutting point or end 4 in some cases may be accurately positioned in the diaphragm by suitable jigs or spacing devices and cemented in place therein by any suitable cement engaging the inner end 5 of the stylus. In some cases where no special reenforcing cementing material is originally used a suitable quantity such as 6 of any desired cementing material, such, for instance, as ambroid or pyroxylin cement or the like may be used for this purpose and allowed to harden while the stylus is in the jig or setting device to ensure its accurate position within the diaphragm.

In some cases diaphragms having duplex or multiple styli may be conveniently formedin this way and as shown in Fig. 3 such a diaphragm may have a coned up or stiffened central portion 9 gradually merging into the relatively flexible edge portion 8 of the diaphragm and may have several styli 10, 11 secured to and projecting from the central portion of the stiffened diaphragm center which may be further stiffened and reenforced by the cement ing material, such as 12, which may be used to hold these styli in position and simultaneously stiffen the diaphragm center at this point. Of course substantially uniform of such cementing material s ould be used so as to ensure uniform pitch and stiffness of the diaphragm and for this purpose the cloth or other fibrous material used for forming such diaphragm should be of substantially uniform weight and character and should contain substantially uniform quantities of the coating or impregnating phenolic condensation cementing material so that the weight, stiffness and strength of the resulting diaphragms will be substantially uniform.

This invention has been disclosed in connection with a number of illustrative embodiments, forms, proportions, elements, parts, shapes, materials, compositions, conditions, and methods of preparation, production and use, to the details of which disclosure the invention is not of course to be limited, since what is claimed as new and what is desired to be secured by Letters Patent is set forth in the appended claims:

1. The diaphragm for dictaphone and similar acoustic instruments formed of fabric carrying cured phenolic condensation cementing material, said diaphragm having a relatively flat flexible edge portion and a coned up projecting stiffened vibrating portion and a plurality of styli projecting through the wall of said diaphragm adjacent and adhesively secured to said projecting portion of the diaphragm.

:2. The-diaphragm for acoustic instruments formed of fibrous material carrying cured phenolic condensation cementing material, said diaphragm having a relatively fiat flexible edge portion and a projecting stiffened vibrating portion and a plurality of styli adhesively secured to said projecting portion of the diaphragm.

3. The diaphragm for acoustic instruments formed of fibrous material carrying cured phenolic condensation cementing material. said diaphragm having a relatively flexible edge portion and a stiffened vibrating portion and a plurality of styli adhesively secured to said vibrating portion of the diaphragm and projecting therefrom at different angles.

4. The diaphragm for dictaphone and similar acoustic instruments formed of fabric carrying cured phenolic condensation cenienting material. said diaphragm having a relatively flat flexible edge portion gradually merging into a coned up stiffened central projecting vibrating portion and a cutting stylus n'ojecting through and adhesively secured to the wall of said diaphragm adja' cent and substantially tangent to the tip of said projecting portion of the diaphragm by stiffening cementing material within the u'ojecting portion of the diaphragm.

5. The diaphragm for dictaphone and similar acoustic instruments formed of fabric carrying cured phenolic condensation cementing material, said diaphragm having a relatively flexible edge portion gradually 'n'ierging into a. coned up stiffened central projecting vibrating portion and a cutting stylus projecting through and adhesively secured to the. wall of said diaphragm adjacent the tip of said projecting portion of the diaphragm. v

6. The diaphragm for acoustic instruments formed of fabric carrying cured phenolic condensation cementing material, said diaphragm having a relatively flexible edge portion and a stiffened vibrating portion and a. stylus adhesively secured to the wall of said diaphragm and projecting through said vibrating portion of the diaphragm.

7. The diaphragm for dictaphone and similar acoustic instruments formed of fllfl'OUS material carrying cured phenolic condensation cementing and stiffening material,

said diaphragm having a relatively fiat flexible edge portion and a substantially conical projecting stiffened central portion and a stylus projecting through the wall of said diaphragm adjacent and substantially tangent to the tip of said projecting portion and adhesively secured in position by cementing material Within said projecting portion of the diaphragm.

8. The diaphragm for dictaphone and similar acoustic instruments formed of fibrous material carrying cured phenolic condensation cementing and stiffening material, said diaphragm having a relatively flexible edge portion and a substantially projecting stiffened central portion and a stylus projecting through the wall of said diaphragm adjacent to the tip of said projecting portion and adhesively secured in position by cementing material within said projecting portion of the diaphragm.

9. The diaphragm for dicta hone and similar acoustic instruments Formed of fibrous material carrying cured phenolic con densation cementing and stifi'emng material,

stiffened portion and a stylus pro ecting through the Wall of said diaphragm adjacent 'to the tip of said projecting portion and adhesively secured in position by cementing material.

10. The diaphragm for acoustic instruments formed of fabric carrying cementing material said diaphragm having a relatively flexible edge portion and a substantially projecting conoidal stiffened vibrating portion and a stylus adhesively secured to said diaphragm adjacent the tip of said vibrating portion of the diaphragm.

11. The diaphragm for dictaphone and similar acoustic instruments ormed of fibrous material carrying cementing and stiffening material, said diaphragm having a relatively flexible edge portion and a substantially projecting stiffened portion and a stylus secured adjacent the tip of said projecting portion.

HENRY C. EGERTON. 

